Numerical Analysis of the LDMOS With Side Triangular Field Plate

A Lateral Double-diffused Metal Oxide Semiconductor (LDMOS) with side triangular field plate (STFP) is proposed for improving the breakdown voltage (BV) and reducing the specific on-resistance (R
_on,sp
). The main feature of the novel LDMOS is the STFPs at both ends of the drift region, and they are fabricated into the dielectric pillars. With the introduction of the STFPs, the electric field peaks at the P-well/N-drift and N+/N-drift junctions are reduced effectively. The STFPs together with the dielectric pillars modulate the surface and vertical electric field distributions, which enhances the BV. Meanwhile, the doping concentration of the silicon pillars in the drift region is optimized and thus reduces the R
_on,sp
. The simulation results indicate that the BV of 379 V and the R
_on,sp
of 37.3 mΩ·cm
²
are achieved by the STFP-LDMOS. The figure of merits (FOM) of the STFP-LDMOS is 2.7 times compared with the conventional LDMOS without STFPs. The STFP-LDMOS demonstrates a great trade-off between the R
_on,sp
and BV.